1. Field of the Invention
This invention relates to method of making silicone emulsions which yield an elastomer upon removal of the water at ambient conditions.
2. Background Information
Compositions comprising an organohydrogenpolysiloxane, an alpha, omega-dihydroxydiorganopolysiloxane and a platinum catalyst are taught in U.S. Pat. No. 3,867,343, issued Feb. 18, 1975.
Silicone paper release coatings are taught in U.S. Pat. No. 4,190,688, issued Feb. 26, 1980. The emulsion comprises a vinyl-containing polydiorganosiloxane having hydroxyl endblocking, a hydride cross-linking agent, water, and an emulsifying agent. The composition can be cured either with a tin salt of a carboxylic acid or it can be cured with a platinum complex catalyst.
A latex of crosslinked silicone is prepared in U.S. Pat. No. 4,248,751, issued Feb. 3, 1981, by emulsifying a vinyl endblocked polydiorganosiloxane and an organosilicon compound having silicon-bonded hydrogen atoms with water and a surfactant, adding platinum catalyst, and then heating the emulsion. Colloidal silica can be added to the emulsion to provide a tougher product.
A method of producing a polydiorganosiloxane latex is taught in U.S. Pat. No. 4,568,718, issued Feb. 4, 1986. The method homogenizes a mixture of hydroxyl endblocked polydiorganosiloxane, a silane, a surface active anionic catalyst and water. After maintaining the emulsion until a crosslinked polymer is formed, the emulsion is admixed with base to a pH of greater than 7. The resulting emulsion can be reinforced by adding colloidal silica sol.
Another method of producing aqueous latex of crosslinked polydiorganosiloxane is taught in U.S. Pat. No. 4,618,645, issued Oct. 21, 1986. This method admixes hydroxyl endblocked polydiorganosiloxane, alkoxy silicone compound, anionic emulsifying agent, and water. The mixture is homogenized, then the emulsion is admixed with surface active anionic catalyst and allowed to react. The reaction is halted by adding base to a pH of greater than 7.